1. Field of the Invention
The invention relates to a seal assembly having a laminated structure.
2. Brief Description of the Related Art
Modern large industrial gas turbines have a shielded combustor such as known from US-B1-6,450,762. Due to the ever greater need for efficiency and combustor stability, the arrangement requires primary to secondary air system seals to be fitted. Driven by the work on known combustor systems, the seals are exposed to ever-higher temperatures, extending to a temperature up to 1500° C. on the hot gas side. It is this thermal exposure that drives the need to define a seal assembly that can live with these temperatures while remaining resilient and responsive to system movement. Highly stressed metals are subject to severe stress relaxation at high temperatures, rendering them useless as resilient sealing elements under such conditions. Even the so called nickel based super alloys such as Inconel 718 and other materials show little ability to withstand exposure to high temperatures beyond 700° C. in a stressed condition without suffering severe stress relaxation and/or creep.
Conventional solutions use cooled seals whereby substantial quantities of cooling air flow are required. This use of cooling reduces the efficiency of the gas turbine and can impair flame stability.